Abrasive disk support



Oct. 28, 194-1. I slEBERT ET AL 2,260,644

ABRAS IVE DISK SUPPORT Filed March 25, 1939 lNVENTOR.

Patented Oct. 28, 1941 ABRASIVE DISK SUPPORT Albert F. Siebert, Milwaukee, and Wendell K.

Beckwith, Shorewood, Wis, asslgnors to Milwaukee Electric Tool Corporation, Milwaukee, Wis., a corporation of Wisconsin Application March 25, 1939, Serial No. 264,074

2 Claims.

The present invention relates generally to improvements in the art of grinding and polishing surfaces, and relates more specifically to improvements in the construction and operation of rotary supports for abrasive disks or the like.

Generally defined, an object of the present invention is to provide a new and useful abrasive disk support which is simple and durable in construction and which is also flexible in use and eflicient in operation.

Many different types of abrasive and polishing disk supports have heretofore been proposed and used with more or less success and for diverse purposes. When such assemblages are utilized forthe purpose of producing smooth blending of a metal surface or the like with an adjacent painted or enameled surface preparatory to applying a final coating to both surfaces, it is desirable to provide an extremely flexible and resilient distortable support for the revolving finishing disk. Heretofore, this flexibility has been obtained primarily by providing a pneumatic, rubber or felt cushion between a relatively rigid revolving carrier and the abrasive disk, so that by applying pressure to the working face of the disk, it could be distorted and thus caused to readily conform with the surface being finished. These intermediate cushions not only complicate the assemblages, but they also deteriorate rapidly, especially when subjected to moisture, and they also lose their flexibility and resiliency, thereby precluding the possibility of properly finishing and feather-edging delicate paint jobs.

It is therefore a more specific object of the present invention to provide an improved finishing disk support of the rotary type, which is extremely flexible and resilient and which will not lose these characteristics when exposed to moisture and to moderate variations in temperature.

Another specific object of this invention is to provide an improved feather-edging assemblage comprising an abrasive or polishing disk and a rotary backing or support for the disk, wherein the backing is formed so as to make it possible to most effectively dress curved surfaces of various forms and shapes.

A further specific object of the invention is to provide a simplified abrasive support comprising a permanently curved spring metal disk having means for quickly and effectively attaching the same to a power unit.

Still another specific object of the present invention is to provide a new and useful multiple metallic disk for supporting abrasive or polishing materials, which may be rapidly attached to or removed from a rotary driving member.

An additional specific object of this invention is to provide an improved backing or support for abrasive disks or the like, which will permit maximum utilization of the abrasive material in a most effective manner.

A further specific object of the present invention is to provide a support for various types of abrasive disks and materials, which may be manufactured and sold at moderate cost, and which avoids undesirable projection of nonabrasive parts or surfaces beyond the zone of action of the abrasive or polishing material.

These and other specific objects and advantages of the invention will be apparent from the following detailed description.

A clear conception of the several features constituting the present improvement, and of the mode of constructing, of assembling, and of utilizing abrasive disk supports built in accordance with the invention, may be had by referring to the drawing accompanying and forming a part of this specification wherein like reference characters designate the same or similar parts in the various views.

Fig. 1 is a central section through a flat multiple disk support for abrasive disks, the support comprising three coacting disks of different diameters;

Fig. 2 is a similar section through the assemblage of Fig. l, with the larger of the three supporting disks removed and the abrasive disk correspondingly reduced in diameter;

Fig. 3 is a central section through a curved multiple disk support for abrasive disks, the support comprising several coacting disks of different diameters;

Fig. 4 is a similar section through the assemblage of Fig. 3, with the larger supporting disk removed and the abrasive disk correspondingly reduced in diameter;

Fig. 5 is a central section through one of the improved single curved support assemblages;

Fig. 6 is a plan view of the assemblage of Fig. 1, looking toward the abrasive disk;

Fig, 7 is an enlarged central section through the central or hub portion of the assemblages of Figs. 1 to 4 inclusive, with the abrasive disk clamp removed; and

Fig. 8 is a section through the assemblage of Fig. 7, taken along the irregular line 8-8.

While the improved abrasive supports have been illustrated and described herein as being used in conjunction with relatively fiat circular abrasive disks and as being applicable to a power driven shaft of a particular type, it is not the intent to thereby unnecessarily restrict the scope or untility of the invention.

Referring specifically to Figs. 1 and 2, the improved assemblage shown therein comprises in general a main supporting disk ID of desirably large diameter formed of relatively thin and resilient sheet metal and having a central opening; an intermediate auxiliary supporting disk H of smaller diameter than the disk It formed of similar material and having a central opening alinable with that of the main disk I; another auxiliary relatively thin and resilient metal disk l2 of somewhat smaller diameter than the intermediate disk ll, secured to a hub l3 by means of a central bushing ll having a central bore alinable with the central openings in the disks Hi, I I, and also having an inwardly extending rounded projection IS; a bored attaching sleeve it formed for snug coaction with the bore of the bushing I4 and having an annular outer groove interlockable with the projection I5, the sleeve It also having a tapered integral flange l8 formed for coaction with the disks N, U adjacent to the central openings therein; a relative- 1y flat abrasive disk l9 normally engageable with the outer face of the supporting disk I0, and having a central portion adapted to coact with the outer tapered surface of the sleeve it through the adjacent portions of the disks III, II; and a clamping nut 2|) having a tapered face adapted to coact directly with the abrasive face of the disk I! and being provided with internal screw threads which are cooperable with a threaded stud 2| formed integral with a rotary central driving member 22 snugly fitting the bore of the sleeve l6.

As previously indicated, the support disks IO, N, l2 are formed of relatively thin, highly flexible and resilient metal such as spring steel or bronze, and the peripheral edges of these disks may be reenforced and finished by folding the same inwardly over the backs of the disks III, I I, I2, although this reenforcement may not be necessaryor desirable in some cases. The inner edges of the disks III, II, |2 adjacent the central openings therein may also be distorted to fit the taper of the sleeve flange I8, and the bushing I may be permanently secured to the hub" in any convenient manner and serves to fixedly attach the smallest disk [2 to this hub. The hub I3 is preferably formed of light metal and may be provided with an indicating arrow 23 shown in Fig. 8 and located in radial alinement with the internal projection l of the bushing l4, and as clearly illustrated in Fig. "l, the central clamping sleeve I6 is provided with a longitudinal recess 24 extending outwardly from the groove H to permit the projection l5 to be inserted within the annular groove on the order of a bayonet joint. The attaching nut 20 which serves to clamp the supporting and the abrasive disks to the driving member 22, also serves to clamp the bushing l4 against possible rotation relative to the sleeve l6 when the assemblage is in use, and the driving member 22 may be any rotary shaft which in the present case is the shaft of a portable electric tool 25. The member 22 is formed to snugly fit the bore of the sleeve l8 and has a flange 26 remote from the stud 2| against which the bushing l4 and sleeve l6 are adapted to be clamped by the nut 20. While Fig. 1 shows a circular abrasive disk IQ of maximum diameter mounted upon the supporting assemblages, the

disk ll of Fig. 2 has been reduced to conform with the diameter of the intermediate supporting disk since the main disk It has been removed.

Referring specifically to Figs. 3 and 4, the improved assemblage illustrated therein is similar to that of Figs. 1 and 2, except that the supporting disks are not plane faced, but are curved or at least have their peripheral edges off-set with respect to their central portions. The main disk 21 and the auxiliary supporting disk 28 are curved near their peripheries, and do not normally contact the abrasive disks l9, I! at these curved peripheral portions. The smallest disk 29 inthis assemblage is preferably of considerably smaller diameter than the intermediate disk 22 so as not to interfere materially with the flexibility and resiliency of the curved peripheral portions of the disks 21, 28; and the smallest disk 29 is permanently attached to a modified hub 30 which is secured to the attaching sleeve ll. The disks 21, 22 are again formed of highly resilient and flexible metal such as thin spring steel and except for the modification in disk and hub structures, the assemblage of Figs. 3 and 4 is like that of Figs. 1 and 2.

Referring specifically to Fig. 5, the improved assemblage shown therein has only one flexible and resilient curved supporting disk 21 coacting with a small central reenforcing disk 29, these disks being permanently attached to a hub 30 by means of a modified central sleeve 3|, the bushing I4 being omitted. In this embodiment of the invention, the diameter of the support cannot be altered to accommodate abrasive or polishing disks I! of difierent sizes, but the disk assemblage of Fig. 5 is again adapted to be detachably attached to a driving member 22 with the aid of a clamping nut 28 coacting with a threaded stud 2|.

During normal use of the improved abrasive disk supporting assemblages, the abrasive disks l9, l9 together with any of the supporting disks illustrated, may be clamped centrally to the supports and frictionally retained, by merely applying the sleeve l8, 3| to the shaft member 22 and by causing the clamping nut 20 to coact with the stud 2| and with the adjacent surface of the disk ISM! as shown; The tool 25 may then be operated to revolve the abrasive disk at high speed, and by subjecting the active peripheral portion of the surface of the abrasive disk l9, l9 to variable pressure, the supporting disk will be brought in contact with the rear thereof and may be deflected more or less so as to insure smooth finishing of the surface being ground or polished. During such rotation of the disks, the nut 20 will constantly tend to clamp the elements tighter.

With an assemblage such as shown in Fig. 1, the flexibility of the peripheral portion of the main reaction disk It may be varied by either utilizing or by removing the intermediate supporting disk When the extreme peripheral portion of a large abrasive disk l9 has become worn, the disk is can be cut to smaller diameter and converted into a disk I9, whereupon it can -be further utilized in a supporting assemblage such as depicted in Fig. 2. With the combination of elements illustrated in Fig. 3, the flexibility of the peripheral portion of the curved reaction disk 21 may also be varied by either utilizing or by removing the auxiliary disk 28, and when the abrasive disk I9 of Fig. 3 has become excessively worn at its periphery, the worn disk I9 may be a support either of the form shown in Fig. 4 or in Fig. 2, for further use. With the assemblage shown in Fig. 5, the disk diameters cannot be From the foregoing detailed description it will be apparent that our present invention provides an improved abrasive disk support having many advantages over prior similar assemblages.- While it has heretofore been proposed to utilize multiple disk supports for the purpose of being able -to apply abrasive disks of different diameters thereto, these supporting disks were of relatively rigid construction and were not utilized to vary the resiliency and flexibility of the abrasive disk support. It has also heretofore been proposed to attach abrasive disks to their supports only at.

the center, but the peripheral portions of these prior assemblages were not sufficiently resilient to permit efiective feather edging of concave and convex surfaces; and in most of the prior abrasive disk assemblages the abrasive disk clamping or retaining elements were permitted to project beyond the abrasive surface remote from the center lines of the assemblages. With the present improvement, the highly flexible and resilient supporting disk is in each case caused to coact directly with the active portion of the abrasive disk, and no intervening cushions are utilized, thus avoiding possibility of having these cushions become inactive due to deterioration. The spring metal supporting disks have proven highly satisfactory in actual use, and the curved or ofl-set disks 2'! have been found to be extremely satisfactory when working on curved or uneven surfaces. vention is operable by means of a spanner wrench, and has no undesirable outwardly projecting parts which might damage the surfaces being finished, and the multiple supports will obviously permit utilization of the abrasive disks I9 to the fullest extentbesides providing means The clamping nut 20 of the present infor effecting variation in the flexibility and resiliency of the supporting structure.

It should be understood that it is not desired to limit this invention to the exact details of construction or to the precise mode of operation,

herein shown and described, for various modifi cationswithin the scope of the claims may occur to persons skilled in the art.

We claim: 1 An abrasive disk assemblage comprising, a permanently convexly curved relatively thin resilient supporting disk of approximately uniform thickness and curved to approximately spherical zone shape throughout its entire area, a relative ly flat and flexible abrasive disk normally contacting only the central portion of said supporting disk, and means for removably clamping only the central portions of said disks together and for rotatably mounting the same, said abrasive disk being formed to remain out of contact with the spherically curved peripheral portion of said supporting disk during idle rotation of the assemblage and the peripheral portions of both disks being engageable and simultaneously deflectable only when said abrasive disk is pressed against the work.

2. An abrasive disk assemblage comprising, a relatively thin resilient supporting disk of approximately uniform thickness throughout its entire area and being convexly curved at its periphery to approximately spherical zone shape and having a central opening and an inwardly curved area adjoining said opening, a relatively flat and flexible abrasive disk normally contacting only the central portion of said supporting disk, and means for removably clamping only the central'portion of said abrasive disk to said inwardly curved area of said supporting disk and for rotatably mounting said disks, said abrasive disk being formed to remain out of contact with the spherical zone area of said supporting disk during idle rotation of the assemblage and the peripheral portions of both disks being engageable and simultaneously deflectable only when said abrasivedisk is pressed against the work.

' ALBERT F. SIEBERT.

WENDEIL K. BECKWITH. 

